A wide variety of transfer printing processes have been described in the prior art. U.S. Pat. Nos. 3,985,602 to Stuart and 4,685,984 to Powers both describe processes for transferring images from a paper sheet to another sheet. The processes may be used for paper to fabric transfer. Stuart describes use of a composite sheet which incorporates a paper carrier sheet with a transparent, thermoplastic sheet having an image retaining, pressure sensitive adhesive layer. A release layer on the adhesive permits a paper protective layer to be adhered until time to use the sheet. In use, the composite sheet is placed against a printed image on the paper, and the pressure sensitive adhesive holds the image while the original paper backing is dissolved away by water. A source of heat such as an iron is used to cause a melting of the thermoplastic layer whereby the plastic, with the adhesive and the image are bonded to the fabric.
Powers teaches another image transfer process for transferring images from paper to fabric, but utilizes a different transfer medium. The Powers process uses a water-impervious, heat-resistant plastic support layer which has a high release coating which supports a contact adhesive, a thermoplastic layer, and a protective layer. After removal of the protective layer, a paper bearing the image to be transferred is placed against the adhesive layer and becomes adherent thereto. The composite obtained thereby is then placed in water to weaken and disintegrate the paper carrier, leaving the image adhered to the plastic sheet. The plastic carrier sheet bearing the image is then applied to the fabric and heat and pressure is applied to fuse the thermoplastic and bound the image to the fabric. The plastic support layer is then removed. The process depends heavily on the qualities of the release coatings. Both the Stuart and Power processes result in a fabric having an image with a plastic layer adherent thereto.
Biegen, in U.S. Pat. No. 3,6607,526, teaches a transfer technique using a contact or pressure sensitive adhesive on a release sheet to pick up an image from a paper sheet. Thereafter, the paper sheet is dissolved in water, leaving the image adhered to the adhesive on the release sheet. The paper that originally held the image is then removed by soaking until the paper has softened so that the paper can be rubbed off. The adhesive is then non-tacky because parts of the paper are adherent to the adhesive. The process differs from the instant process in that the paper must be rubbed from the adhesive, which retains some of the paper and is then non-tacky. The image is then transferred to the fabric. However, the fabric then retains a tacky feel.
All of the prior art techniques described are deficient because the final product retains a fairly heavy layer of the substrate that held the image to the transfer sheet. Fabrics treated by the prior art methods had a stiff, unmanageable quality. The methods described in the first two patents leave a plastic coating over the image. While such a coating may be appropriate for some applications, the effect is undesirable in many instances. The further processing of the product is difficult when the surface with the image has too heavy a layer of transfer material. Furthermore, the resulting image is not appropriate for more delicate artistic applications. Hence, the decorative possibilities with the prior art methods are limited to sports wear and prints wherein no further sewing on the decorated surface is required.
Prior art techniques were sold under the trademarks "Transfer Magic" and "Fabulon". The commercially available products suggest use of the transfer media with printed material or with photocopies of photographs. Hence, it was at least theoretically possible to produce a color image transfer using a color photocopy. In practice, however, such color photocopies do not provide flexibility of coloration, and even with the improved copiers, the applications are limited.